The document discusses acid-base homeostasis, highlighting the chemical and physiological processes that maintain optimal acidity in body fluids. It details the mechanisms of regulation, including chemical buffers, respiratory responses, and renal function, as well as the consequences of imbalances leading to acidosis or alkalosis. The text also outlines the causes, symptoms, and treatments for metabolic acidosis and alkalosis, emphasizing the importance of maintaining proper hydrogen and bicarbonate ion levels.

1. ACID BASE BALANCE
Sanij Singh
MDGP 2nd year
1

2. ACID BASE HOMEOSTASIS
 Acid-Base homeostasis involves
 chemical and
 physiologic
processes responsible for the maintenance of
the acidity of body fluids at levels that allow
optimal function of the whole individual
2

3. ACID BASE HOMEOSTASIS
 The chemical processes –
 first line of defense to an acid or base load
and include the extracellular and
intracellular buffers
 The physiologic processes
 modulate acid-base composition by changes
in cellular metabolism and by adaptive
responses in the excretion of volatile acids
by the lungs and fixed acids by the kidneys
3

4. ACID-BASE BALANCE
4

5. ACID-BASE BALANCE
 Acid - Base balance is primarily
concerned with two ions:
 Hydrogen (H+)
 Bicarbonate (HCO3
- )
5
H+ HCO3
-

6. ACID-BASE
BALANCE
 H+ ion has special
significance
because of the
narrow ranges that
it must be
maintained in order
to be compatible
with living systems
6

7. ACID-BASE REGULATION
7

8. ACID-BASE REGULATION
 Maintenance of pH range in the extracellular
fluids is by three mechanisms:
 1) Chemical Buffers
React very rapidly
(less than a second)
 2) Respiratory Regulation
Reacts rapidly (seconds to minutes)
 3) Renal Regulation
Reacts slowly (hours to days)
8

9. ACID-BASE REGULATION
 Chemical Buffers
 pH buffers in the blood to guard against sudden
changes in acidity
 A pH buffer works chemically to minimize
changes in the pH of a solution
9
Buffer

10. ACID-BASE REGULATION
 Respiratory Regulation
 Carbon dioxide - an important by-product of
metabolism and is constantly produced by cells
 The blood carries carbon dioxide to the lungs
where it is exhaled
10
CO2
CO2 CO2
CO2
CO2
CO2
Cell
Metabolism

11. ACID-BASE REGULATION
 Respiratory Regulation
 With increased breathing,
the blood carbon dioxide level
decreases and the blood
becomes more Base
 With decreased breathing
the blood carbon dioxide level
increases and the blood becomes more Acidic
 By adjusting the speed and depth of breathing,
the respiratory control centers and lungs are
able to regulate the blood pH minute by minute
11

12. ACID-BASE REGULATION
 Kidney Regulation
 Excess acid is excreted by
the kidneys, largely in the
form of ammonia
 The kidneys have some
ability to alter the amount
of acid or base that is
excreted, but this generally
takes several days
12

13. ACIDS
 Physiologically important acids include:
 Carbonic acid (H2CO3)
 Phosphoric acid (H3PO4)
 Pyruvic acid (C3H4O3)
 Lactic acid (C3H6O3)
 These acids are dissolved in body fluids
13
Lactic acid
Pyruvic acid
Phosphoric acid

14. BASES
 Physiologically important bases include:
 Bicarbonate (HCO3
- )
 Biphosphate (HPO4
-2 )
14
Biphosphate

15. pH SCALE
15

16. pH SCALE
 pH equals the logarithm (log) to the base
10 of the reciprocal of the hydrogen ion
(H+) concentration
 H+ concentration in extracellular fluid
(ECF)
16
pH = log 1 / H+ concentration
4 X 10 -8 (0.00000004)

17. pH SCALE
 pH = 4 is more acidic than pH = 6
 pH = 4 has 10 times more free H+
concentration than pH = 5 and 100 times
more free H+ concentration than pH = 6
17
ACIDOSIS ALKALOSIS
NORMAL
DEATH DEATH
Venous
Blood
Arterial
Blood
7.3 7.5
7.4
6.8 8.0

18. pH SCALE
18

19. ACIDOSIS / ALKALOSIS
19

20. ACIDOSIS / ALKALOSIS
 pH changes have dramatic effects on normal
cell function
 1) Changes in excitability of nerve and
muscle cells
 2) Influences enzyme activity
 3) Influences K+ levels
20

21. CHANGES IN CELL
EXCITABILITY
 pH decrease (more acidic) depresses the
central nervous system
 Can lead to loss of consciousness
 pH increase (more basic) can cause over-
excitability
 Tingling sensations, nervousness,
muscle twitches
21

22. INFLUENCES ON ENZYME
ACTIVITY
 change in pH can alter the shape of the
enzyme rendering it non-functional
 Changes in enzyme structure can result in
accelerated or depressed metabolic actions
within the cell
22

23. INFLUENCES ON K+ LEVELS
 When reabsorbing Na+ from the filtrate of
the renal tubules K+ or H+ is secreted
(exchanged)
 Normally K+ is
secreted in much
greater amounts
than H+
23
K+
K+
K+
K+
K+
K+
K+
Na+
Na+
Na+
Na+
Na+
Na+
H+

24. INFLUENCES ON K+ LEVELS
 If H+ concentrations are high (acidosis) than
H+ is secreted in greater amounts
 This leaves less K+ than usual excreted
 The resultant K+ retention can affect cardiac
function and other systems
24
K+
K+
K+
Na+
Na+
Na+
Na+
Na+
Na+
H+
H+
H+
H+
H+
H+
H+
K+
K+
K+
K+
K+

25. ACIDOSIS / ALKALOSIS
 Normal ratio of HCO3
- to H2CO3 is 20:1
 H2CO3 is source of H+ ions in the body
 Deviations from this ratio are used to
identify Acid-Base imbalances
25
BASE ACID
H2CO3
H+
HCO3
-

26. ACIDOSIS / ALKALOSIS
 Acidosis and Alkalosis can arise in two
fundamentally different ways:
 1) Excess or deficit of CO2
(Volatile Acid)
Volatile Acid can be eliminated by the
respiratory system
 2) Excess or deficit of Fixed Acid
Fixed Acids cannot be
eliminated by the
respiratory system
26

27. ACIDOSIS / ALKALOSIS
 Normal values
 pH = 7.35-7.45
 PCO2 = 35-45 mm Hg
 HCO3
- = 22-26 meq/L
 PaO2 = 80-100
 O2 sat =95-98%
27

28. ACIDOSIS
 A decrease in a normal 20:1 base to
acid ratio
 An increase in the number of
hydrogen ions
(ex: ratio of 20:2 translated to 10:1)
 A decrease in the number of bicarbonate
ions (ex: ratio of 10:1)
 Caused by too much acid or too little base
28
ACID BASE

29. ALKALOSIS
 An increase in the normal 20:1 base to acid
ratio
 A decrease in the number of hydrogen
ions
(ex: ratio of 20:0.5 translated to 40:1)
 An increase in the number of bicarbonate
ions (ex: ratio of 40:1)
 Caused by base excess or acid deficit
29
ACID BASE

30. SOURCES OF HYDROGEN IONS
 1) Cell Metabolism (CO2)
 2) Food Products
 3) Medications
 4) Metabolic Intermediate by-
products
 5) Some Disease processes
30

31. SOURCES OF BICARBONATE
IONS
 1) CO2 diffusion into red blood cells
 2) Parietal cell
secretion of the
gastric mucosa
31

32. 32
CARBON DIOXIDE DIFFUSION
CO2
CO2
Red Blood Cell Systemic Circulation
CO2 H2O H+ HCO3
-
+ +
HCO3
-
Cl-
(Chloride Shift)
CO2 diffuses into the plasma and into the RBC
Within the RBC, the hydration of CO2 is
catalyzed by carbonic anhydrase
Bicarbonate thus formed diffuses into plasma
carbonic
anhydrase
Tissues
Plasma

33. BICARBONATE DIFFUSION
33
Red Blood Cell Pulmonary Circulation
CO2 H2O H+ HCO3
-
+ +
HCO3
-
Cl-
Alveolus
Plasma
CO2
Bicarbonate diffuses back into RBC in pulmonary
capillaries and reacts with hydrogen ions to form
carbonic acid
The acid breaks down to CO2 and water

34. BICARBONATE SECRETION
 Cells of the gastric
mucosa secrete H+
ions into the lumen
of the stomach in
exchange for the
diffusion of
bicarbonate ions into
blood
 The direction of the
diffusion of these
ions is reversed in
pancreatic epithelial
cells 34
Parietal cells of
gastric mucosa
Pancreatic
epithelial cells
HCO3
-
H+
HCO3
-
H+
lumen of
stomach
pancreatic
juice
blood
blood

35. ACIDOSIS / ALKALOSIS
 Deviations from normal Acid-Base status
depending on the source and direction of
the abnormal change in H+ concentrations
 Respiratory Acidosis
 Respiratory Alkalosis
 Metabolic Acidosis
 Metabolic Alkalosis
35

36. ACIDOSIS / ALKALOSIS
 Acidosis and Alkalosis are categorized as
Metabolic or Respiratory depending on
their primary cause
 Metabolic Acidosis and Metabolic
Alkalosis
caused by an imbalance in the
production and excretion of acids or
bases by the kidneys
 Respiratory Acidosis and Respiratory
Alkalosis
caused primarily by lung or breathing
disorders 36

37. METABOLIC ACIDOSIS
37

38. METABOLIC ACIDOSIS
 Occurs when there is a decrease in the
normal 20:1 ratio
 Decrease in blood pH and bicarbonate
level
 Excessive H+ or decreased HCO3
-
38
H2CO3 HCO3
-
1 20
:
= 7.4
1 10
:
= 7.4

39. METABOLIC ACIDOSIS
 Any acid-base
imbalance not
attributable to CO2 is
classified as metabolic
 Metabolic production
of Acids
 Or loss of Bases
39

40. METABOLIC ACIDOSIS
 Metabolic acidosis is always characterized by
a reduction in plasma HCO3
- while CO2
remains normal
40
HCO3
-
CO2
Plasma Levels

41. METABOLIC ACIDOSIS
 Acidosis results from excessive loss of HCO3
-
rich fluids from the body or from an
accumulation of acids
 Accumulation of non-carbonic plasma acids
uses HCO3
- as a buffer for the additional H+
thus reducing HCO3
- levels
41
tic Acid
Muscle Cell

42. METABOLIC ACIDOSIS
 The causes of metabolic acidosis can be
grouped into five major categories
 1) Ingesting an acid or a substance that
is metabolized to acid
 2) Abnormal Metabolism
 3) Kidney Insufficiencies
 4) Strenuous Exercise
 5) Severe Diarrhea
42

43. METABOLIC ACIDOSIS
 1) Ingesting An Acid
 Most substances that cause acidosis when
ingested are considered poisonous
 Examples include
wood alcohol
(methanol) and
antifreeze
(ethylene glycol)
 However, even an overdose
of aspirin (acetylsalicylic acid)
can cause metabolic acidosis
43

44. METABOLIC ACIDOSIS
 2) Abnormal Metabolism
 The body can produce excess acid as a
result of several diseases
One of the most significant is Type I
Diabetes Mellitus
44

45. METABOLIC ACIDOSIS
 Unregulated diabetes
mellitus causes
ketoacidosis
 Body metabolizes fat
rather than glucose
 Accumulations of
metabolic acids
(Keto Acids) cause
an increase in
plasma H+
45

46. METABOLIC ACIDOSIS
 2) Abnormal Metabolism (contd.)
 The body also produces excess acid in the
advanced stages of shock, when lactic
acid is formed through the metabolism of
sugar
46

47. METABOLIC ACIDOSIS
 3) Kidney Insufficiencies
 Kidneys may be unable to
rid the plasma of even the
normal amounts of H+
generated from metabolic
acids
 Kidneys may be also unable
to conserve an adequate
amount of HCO3
- to buffer
the normal acid load
47

48. METABOLIC ACIDOSIS
 3) Kidney Insufficiencies
 This type of kidney malfunction is called
renal tubular acidosis or uremic
acidosis and may occur in people with
kidney failure or with abnormalities that
affect the kidneys' ability to excrete acid
48

49. METABOLIC ACIDOSIS
 4) Strenuous Exercise
 Muscles resort to anaerobic glycolysis
during strenuous exercise
 Anaerobic respiration leads to the
production of large amounts of lactic acid
49
C6H12O6 2C3H6O3 + ATP (energy)
Enzymes
Lactic Acid

50. METABOLIC ACIDOSIS
 5) Severe Diarrhea
 Fluids rich in HCO3
- are released and
reabsorbed during the digestive process
 During diarrhea this HCO3
- is lost from the
body rather than reabsorbed
50

51. METABOLIC ACIDOSIS
 5) Severe Diarrhea
 The loss of HCO3
- without a corresponding
loss of H+ lowers the pH
 Less HCO3
- is available for buffering H+
 Prolonged deep (from duodenum) vomiting
can result in the same situation
51

52. METABOLIC ACIDOSIS
 Signs and symptoms of metabolic
acidosis
 Kussmal’s respirations
 Lethargy
 HA
 Weakness
 N/V
 pH <7.35
 Bicarb <22
 CO2 >38

53. METABOLIC ACIDOSIS
53
-HCO3
- decreases because of excess presence
of ketones, chloride or organic ions
-pH 7.1
1 10
:
= 7.4

54. METABOLIC ACIDOSIS
54
BODY’S COMPENSATION
- hyperactive breathing to “ blow off ” CO2
- kidneys conserve HCO3
- and eliminate H+ ions
in acidic urine
0.75 10
:
CO2
CO2 + H2O
HCO3
- + H+
HCO3
-
+
H+
Acidic urine

55. METABOLIC ACIDOSIS
55
- therapy required to restore metabolic balance
- lactate solution used in therapy is converted
to bicarbonate ions in the liver
H2CO3 HCO3
-
0.5 10
:
Lactate
Lactate
containing
solution

56. METABOLIC ACIDOSIS
 Bicarbonate deficiency(mmol/L) = body
weight(in kg) X 0.4X (desired bicarbonate-
measured bicarbonate)
 Only a rough estimate as ongoing loss is a
dynamic process

57. METABOLIC ACIDOSIS
 In nonurgent condition
 Continuous IV infusion over 4
to 8 hours
 Can be added to 1 liter of D5W
or 0.45% of NaCl
 a 50 ml ampule of
8.4%NaHCO3 provides 50
mmol of bicarbonate
57

58. METABOLIC ACIDOSIS
 When acidosis is severe,
bicarbonate may be given in
Bolus over several minutes
 Goal is to raise arterial Blood
pH to 7.20 or the bicarbonate
to 10 mmol/L
 Danger of hypernatremia,
hyperkapnia, CSF acidosis
or overshoot alkalosis
58

59. METABOLIC ALKALOSIS
59

60. METABOLIC ALKALOSIS
 Elevation of pH due to an increased 20:1
ratio
 May be caused by:
An increase of bicarbonate
A decrease in hydrogen ions
 Imbalance again cannot be due to CO2
 Increase in pH which has a non-
respiratory origin
60
7.4

61. METABOLIC ALKALOSIS
 A reduction in H+ in the case of metabolic
alkalosis can be caused by a deficiency of
non-carbonic acids
 This is associated with an increase in HCO3
-
61

62. METABOLIC ALKALOSIS
 Can be the result of:
 GASTROINTESTINAL HYDROGEN LOSS
 Removal of gastric secretions (vomiting, tube drainage)
 Loss of intestinal secretions (villous adenoma or
factitious diarrhea due to laxative abuse )
 Ingestion of Alkaline Substances
 safe limit 1000 meq of sodium bicarbonate per day
62

63. METABOLIC ALKALOSIS
 Can be the result of: (contd.)
 RENAL HYDROGEN LOSS
 Primary mineralocorticoid excess
 Loop or thiazide diuretics
 Posthypercapnic alkalosis
 Hypercalcemia and the milk-alkali syndrome
 INTRACELLULAR SHIFT OF HYDROGEN
 Hypokalemia
 CONTRACTION ALKALOSIS
 Administration of intravenous loop diuretics to induce
rapid fluid removal in a markedly edematous patient is
the most common cause of a contraction alkalosis

64. Metabolic Alkalosis
Check a Spot Urine Chloride
 Chloride Responsive
 Urine Cl- <15 meq/L
 Loss of gastric acid.
 Diuretics.
 Volume depletion.
 Post hypercapnia.
 Chloride Resistant
 Urine Cl- >25 meq/L
 Mineralcorticoid
excess.
 Potassium depletion.

65. Metabolic Alkalosis
 Signs and symptoms of metabolic
alkalosis
 Hyperventilation
 Dysrhythmias
 Dizziness
 Hypertonic muscle tetany
 pH >7.45
 Bicarb >26
 Hypokalemia
 hypocalcemia

66. METABOLIC ALKALOSIS
 Reaction of the body to alkalosis is to lower
pH by:
 Retain CO2 by decreasing breathing rate
 Kidneys increase the retention of H+
66
CO2
CO2
H+
H+
H+
H+

67. METABOLIC ALKALOSIS
67
- pH = 7.7
- HCO3
- increases because of loss of chloride
ions or excess ingestion of NaHCO3
1 40
:

68. METABOLIC ALKALOSIS
68
BODY’S COMPENSATION
- breathing suppressed to hold CO2
- kidneys conserve H+ ions and eliminate HCO3
-
in alkaline urine
1.25 30
CO2 + H2O
HCO3
- + H+
HCO3
-
H+
+
Alkaline urine
:

69. METABOLIC ALKALOSIS
69
- Therapy required to restore metabolic balance
- HCO3
- ions replaced by Cl- ions
H2CO3 HCO3
-
1.25 25
:
Cl-
Chloride
containing
solution

70. METABOLIC ALKALOSIS
 Initial therapy
 Volume deficits with 0.9% NaCl
 Correct hypokalemia
 Patient with vomiting or NG suctioning may
benefit with H2 receptor antagonists or other
acid suppressing agents.

71. METABOLIC ALKALOSIS
 Edematous patients
 Chloride correction not useful
 Acetazolamide 5mg/kg/day IV or orally
faciliitate fluid mobilization and decrease renal
bicarbonate reabsorption.
 Increase tolerance in 2 to 3 days

72. METABOLIC ALKALOSIS
 Severe alkalosis (bicarbonate 40 mmol/L)
 Can give Ammonium chloride --- hepatically converted
to urea and HCl.
 Amount needed = 0.2 X weight in kg X (103-serum Cl
in mmol/L )
 Prepared by 100 to 200 mmol (20 to 40 mL of the
26.75% ) to 500ml to 1 L of 0.9% NaCl at rate not
exceeding 5ml/minutes
 Give half of needed then measure ABG and Cl level
 Contraindicated in Hepatic failure.

73. METABOLIC ALKALOSIS
 Can also give HCl
 0.1 N HCl IV
 Required amount = 0.5 X weight in kg X (103-
serum Cl in mmol/L )
 To prepare 0.1 N 100 mmol 0f HCl in 1 L of
sterile water.
 Given via CV catheter over 24 hours
 Can safely reduce bicarbonate level by 8 to 12
mmol/L over 12 to 24 hours.

74. RESPIRATORY ACIDOSIS
 Caused by hyperkapnia due to
hypoventilation
 Characterized by a pH decrease and
an increase in CO2
74
CO2 CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2 CO2
CO2
pH
pH

75. RESPIRATORY ACIDOSIS
75

76. RESPIRATORY ACIDOSIS
 Normally when CO2 builds up, the pH of the
blood falls and the blood becomes acidic
 High levels of CO2 in the blood stimulate the
parts of the brain that regulate breathing,
which in turn stimulate faster and deeper
breathing
76

77. RESPIRATORY ACIDOSIS
 Decreased CO2 removal can
be the result of:
1) Obstruction of air passages
2) Decreased respiration
(depression of respiratory
centers)
3) Decreased gas exchange
between pulmonary
capillaries and air sacs of
lungs
4) Collapse of lung
5) Others like Sepsis and
Burns 77

78. RESPIRATORY ACIDOSIS
 Signs and symptoms
 Dyspnea
 Disorientation
 Coma
 Dysrythmias
 Ph <7.35
 PaCo2 >45
 Hypokalemia

79. RESPIRATORY ACIDOSIS
79
- metabolic balance before onset of acidosis
- pH = 7.4
H2CO3 HCO3
-
1 20
:
H2CO3 : Carbonic Acid
HCO3
- : Bicarbonate Ion
(Na+) HCO3
-
(K+) HCO3
-
(Mg++) HCO3
-
(Ca++) HCO3
-

80. RESPIRATORY ACIDOSIS
80
-breathing is suppressed holding CO2 in body
-pH = 7.1
2 20
:
CO2
CO2
CO2
CO2

81. RESPIRATORY ACIDOSIS
81
BODY’S COMPENSATION
-kidneys conserve HCO3
- ions to restore the
normal 40:2 ratio (20:1)
-kidneys eliminate H+ ion in acidic urine
2 30
:
HCO3
-
H2CO3
HCO3
-
H+
+
acidic urine

82. RESPIRATORY ACIDOSIS
82
- therapy required to restore metabolic balance
- lactate solution used in therapy is converted to
bicarbonate ions in the liver
H2CO3 HCO3
-
2 40
:
Lactate
Lactate
LIVER
HCO3
-

83. RESPIRATORY ACIDOSIS
Treatment for respiratory acidosis?
 Treat underlying cause
 Support ventilation
 Correct electrolyte imbalance
 IV sodium bicarbonate

84. RESPIRATORY ALKALOSIS
 Can be the result of:
 Anxiety, emotional disturbances
 Respiratory center lesions
 Fever
 Salicylate poisoning (overdose)
 High altitude (low PO2)
 Overventilation with ventilator
 CNS trauma/tumor
 Emphysema, Pneumonia
84

85. RESPIRATORY ALKALOSIS
Signs and symptoms of respiratory
alkalosis
 Tachycardia
 SOB
 Syncope, Coma
 Seizures
 Numbness/tingling of extremities
 Blurred vision
 pH >7.45, CO2 < 35

86. RESPIRATORY ALKALOSIS
 Normal 20:1 ratio is increased
 pH of blood is above 7.4
86
H2CO3 HCO3
-
1 20
:
= 7.4
0.5 20
:
= 7.4

87. RESPIRATORY ALKALOSIS
87
-respiratory alkalosis
-pH = 7.7
-hyperactive breathing “ blows off ” CO2
0.5 20
:
CO2
CO2 + H2O

88. RESPIRATORY ALKALOSIS
88
BODY’S COMPENSATION
- kidneys conserve H+ ions and eliminate HCO3
- in
alkaline urine
0.5 15
:
HCO3
-
Alkaline Urine

89. RESPIRATORY ALKALOSIS
89
- therapy required to restore metabolic balance
- HCO3
- ions replaced by Cl- ions
H2CO3 HCO3
-
0.5 10
:
Cl-
Chloride
containing
solution

90. ACIDOSIS
90
decreased
removal of
CO2 from
lungs
failure of
kidneys to
excrete
acids
metabolic
acid
production
of keto acids
absorption of
metabolic acids
from GI tract
prolonged
diarrhea
accumulation
of CO2 in blood
accumulation
of acid in blood
excessive loss
of NaHCO3
from blood
metabolic
acidosis
deep
vomiting
from
GI tract
kidney
disease
(uremia)
increase in
plasma H+
concentration
depression of
nervous system
accumulation
of CO2 in blood
accumulation
of acid in blood
excessive loss
of NaHCO3
from blood
respiratory
acidosis

91. 91
ALKALOSIS
respiratory
alkalosis
anxiety overdose
of certain
drugs
high
altitudes
prolonged
vomiting
ingestion of
excessive
alkaline drugs
excess
aldosterone
hyperventilation
loss of CO2 and
H2CO2 from
blood
loss of acid accumulation
of base
metabolic
alkalosis
decrease
in plasma H+
concentration
overexcitability
of nervous
system
hyperventilation
loss of CO2 and
H2CO2 from
blood
loss of acid accumulation
of base

92. Mixed Acid-Base Disorder
 When 2 or 3 primary disturbances occur
simultaneously
 When significant deviation from the
predictable compensation pattern is observed.

93. Mixed Acid-Base Disorder
 Metabolic Acidosis and Respiratory
Acidosis
 Cardipulmonary arrest
 Severe pulmonary edema
 Salicylate and sedative overdose
 Pulmonary disease with renal failure or sepsis

94. Mixed Acid-Base Disorder
 Metabolic Acidosis and Respiratory
Alkalosis
 Salicylate overdose
 Sepsis
 combined hepatic and renal insufficiency

95. Mixed Acid-Base Disorder
 Metabolic Alkalosis and Respiratory
Acidosis
 Chronic pulmonary disease with superimposed
 Diuretic therapy
 Steroid therapy
 Vomiting
 Reduction of hyperkapnia with mechanical
ventilation

96. Mixed Acid-Base Disorder
 Metabolic Alkalosis and Respiratory
Alkalosis
 Pregnancy with vomiting
 CLD treated with diuretic therapy
 CP arrest with bicarb tx and mechanical
ventilation

97. Mixed Acid-Base Disorder
 Metabolic acidosis and alkalosis
 Vomiting superimposed on
 Renal failure
 DKA
 Alcoholic ketoacidosis

98. RESPONSES TO:
ACIDOSIS AND ALKALOSIS
 Mechanisms protect the body against life-
threatening changes in hydrogen ion
concentration
 1) Buffering Systems in Body Fluids
 2) Respiratory Responses
 3) Renal Responses
 4) Intracellular Shifts of Ions
98

99. 1) Buffer Systems
2) Respiratory Responses
3) Renal Responses
4) Intracellular Shifts of Ions
99

100. BUFFERS
 Buffering systems provide an immediate
response to fluctuations in pH
 1) Phosphate
 2) Protein
 3) Bicarbonate Buffer System
100

101. PROTEIN BUFFER SYSTEM
 2) Protein Buffer System
 Behaves as a buffer in both plasma and
cells
 Hemoglobin is by far the most important
protein buffer
101

102. PROTEIN BUFFER SYSTEM
 Most important
intracellular buffer
(ICF)
 The most plentiful
buffer of the body
102

103. PROTEIN BUFFER SYSTEM
103
-
-
-
- - - -
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- - - -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ +
+
+
+
+
+
+
+ +
+
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
H+
H+
H+
H+ H+ H+ H+ H+ H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+

104. BICARBONATE BUFFER SYSTEM
 3) Bicarbonate Buffer System
 Predominates in extracellular fluid (ECF)
HCO3
- + added H+ H2CO3
104
HCO3
-
H2CO3

105. BICARBONATE BUFFER SYSTEM
 This system is most important because the
concentration of both components can be
regulated:
 Carbonic acid by the respiratory system
 Bicarbonate by the renal system
105

106. BICARBONATE BUFFER SYSTEM
106
Loss of HCl
Addition of lactic acid
H+ HCO3
-
H2CO3
H2O
CO2 + +
Exercise
Vomiting

107. 1) Buffer Systems
2) Respiratory Responses
3) Renal Responses
4) Intracellular Shifts of Ions
107

108. RESPIRATORY RESPONSE
 Neurons in the medulla oblongata and pons
constitute the Respiratory Center
 Stimulation and limitation of respiratory
rates are controlled by the respiratory center
 Control is
accomplished by
responding to CO2
and H+
concentrations in
the blood
108

109. 1) Buffer Systems
2) Respiratory Responses
3) Renal Responses
4) Intracellular Shifts of Ions
109

110. RENAL RESPONSE
 The kidney compensates for Acid - Base
imbalance within 24 hours and is responsible
for long term control
 The kidney in response:
 To Acidosis
Retains bicarbonate ions and eliminates
hydrogen ions
 To Alkalosis
Eliminates bicarbonate ions and retains
hydrogen ions
110

111. 1) Buffer Systems
2) Respiratory Responses
3) Renal Responses
4) Intracellular Shifts of Ions
111

112. ELECTROLYTE SHIFTS
112
cell
H+
K+
Acidosis
Compensatory Response Result
- H+ buffered intracellularly
- Hyperkalemia
H+
K+
cell
Alkalosis
Compensatory Response Result
- Tendency to correct alkalosis
- Hypokalemia

113. END
ACID - BASE BALANCE
113